Process for the selective cracking of hydrocarbons



` Aug. 25, 1936. .1. F. DoNNl-:LLY

PROCESS FOR THE SELECTIVE CRACKING OF HYDROCARBONS Filed March l5, 1935 2 Sheets-Sheet 2 INVENTOR,

Patented Aug. 25, 1936 l UNITED STATES PATENT OFFICE v PROCESS FOR THE SELECTIVE CRACKING 0F HYDROCARBONS Joseph F. Donnelly, Lernout, lll., asslgnor to Donnelly Process Corporation, Chicago, lll., a.

corporation of Nevada My invention relates to a method for the selective cracking of hydrocarbons and particularly to a method for the cracking treatment of petroleum hydrocarbons wherein the production of detrimental carbon is avoided and the degree of cracking practiced is further governed by the. molecular structure of the more complex fractions of the stock to be converted.

A general object of my invention is to provide for the pyrolytic treatment of hydrocarbon fluids wherein the more complex fractions thereof undergo a molecular rearrangement productive of compounds of improved characteristics.

-Another object of my invention is to provide, under such pyrolytic treatment as immediately above described, for the production of crackable fractions of constant characteristics, and to subject selectlve fractions thereof to coil cracking conditions of temperature, time and. pressure, cooperatively formative of lighter and heavier fractions respectively adapted to subsequent vapor phase and liquid or liquid-vapor phase cracking. i

A further object of the invention is to provide for the separate and simultaneous py; Jlytic cracking treatment of selective fractions under different cracking conditions best suited to produce a maximum gasoline yield of desirable octane rating unaccompanied by the formation of detrimental carbon.

A specic purpose of the invention is to provide a cracking process for the molecular alteration of relatively heavy hydrocarbons, such as crude oil or topped crude, into gasoline and other light hydrocarbons and into low viscosity residual oil, wherein a distillate fraction such as gas oil or lubricating distillate intermediately derived by a known method of distillation from such relatively heavy hydrocarbons, is submitted to moderate cracking conditions (illustratively 825 to 925 F.) in a primary zone for a period formative of substantial quantities of fractions boiling under and above approximately 625 F. respectively, the thus obtained fractions released to and separated in a second zone, released from said second zone and the fraction boilngvunder approximately 625 F. subjected in a third zone to vapor phase cracking under conditions formative of gasoline of high anti-knock rating, the products of such vapor phase treatment while still undergoing active cracking .commingled inI a 'fourth zone with aportion -of the fraction boiling above approximately 625 F. separated in said second zone and/or with the relatively heavy charge oil (topped crude, etc.) at a temperature permitting further cracking of the latter in such zone; wherein the treatment is continued in said fourth zone for a period formative of an additional quantity of fractions lighter than the charge oil accompanied by a substantial viscosity reduction thereof, but under conditions inhibitive of detrimental free carbon formation4 densation according to standard practice.

In carrying out the invention, I preferably initially subject the raw stock to be converted (crude oil, reduced crude, etc.) to a moderately high temperature and pressure, but under so short a time factor that the initial conversion is of a relatively mild order; the reaction being more of a molecular rearrangement of the heavier constituents, as evidenced by reductionin viscosity of the heavier fraction.

The portion of heavy distillate such as raw and/or recycle gas oil obtained through partial vaporization of the raw stock treated as above described, and/or obtained from the cracked products, is primarily subjected to so-called liquid, or liquid-vapor phase cracking, preferably in a coil of conventional type where a moderately high temperature and pressure (illustratively 825 to 925 F. and 100 to 1000 lbs., respectively) is imposed under a time factor formative of low octane rating gasoline and other relativelylight fractions, but inh-ibitive of substantial asphaltic degradation and wherein such time and temperature treatment is further regulated toeffect a limited molecular change of the oil undergoing treatment permitting additional subsequent cracking thereof productive of a further quantity of gasoline and other relat'vely light fractions. Summarizing; such primary treatment causes a rearrangement of the molecular struc-V ture resulting in the formation of a wider boiling range product which is subsequently separated into two major fractions, one as liquid boiling above approximately 625 F., the other' jecting the vaporous portion to an increased temperature for a period formative of additional gasoline of desired higher octane rating, then admixing in a separate zone a portion of the vapor cracked products while at a high cracking rate temperature (illustratively 925 to 1125 F.) with a portion of the separated liquid product and/or heavy charge oil supplied from an extraneous source, also at a cracking temperature (illustratively '775 to 900 F.) and carefully regulating the duration of treatment in said zone as to inhibit detrimental free carbon separation but permit of the production of an additional amount of gasoline and other relatively light fractions while maintaining therein a pressure preventive of complete vaporization of fractions otherwise vaporizable at the obtaining temperature, a gasoline of 65 or higher octane rating is obtained.

Although according to the invention primary subjection of heavy hydrocarbons to the pyrolytic treatment before described is vnecessary to produce a cracking stock therefrom that will Withstand vapor phase cracking temperatures (illustratively 925 to 1l25 F.) in order to yield a high percentage of gasoline of superior octane rating, i. e., 65 or above, the supply of such cracking stock may be augmented through the introduction of corresponding fractions derived from extraneously supplied gasoline, naphtha or kerosene of low octane value which require pyrolytlc treatment to effect the desired degree of molecular change.

An additional quantity of gasoline is produced by admixing the products from the vapor phase cracking coil, while still in an active state of cracking, with preheated heavy fractions such as lubricating oil distillate, topped crude oil, etc., followed by maintaining such admixture at an active cracking temperature in a separate zone (well-insulated to avoid heat loss) under a pressure preventive of complete vaporization of the vaporizable fractions obtaining in said zone. If required, the maintenance of an active cracking temperature of the mixture may be aided by applying heat to the last mentioned zone.

.- The .present invention employs at least two, and may employ three, of the well-known and Aunderstood pyrogenic phases of cracking; that is vapor phase, liquid-vapor phase, and liquid phase, working co-operatively andsimul'taneously in a new m'anner as to produce better economic results than have heretofore been obtainable.

The oil undergoing treatment 'in coils 21 and 21 enters in liquid phase and may or may not progress into liquid-vapor phase depending on'the depth of cracking and the pressure obtaining therein. i

'I'he oil undergoing treatment in coils 33 and 33 enters in vapor phase, or it may enter in liquid phase and be substantially completely vaporized before, or simultaneously with cracking therein.

The present invention provides a plurality of simultaneously operative, selective, differential heat treatments whereby a preferred fraction is treated in one zone to cracking conditions formative of fractions best suited to vapor phase, and to liquid or liquid-vapor phase cracking, respectively, whereby such converted fraction is separated into lvaporous and liquid fractions in a separate zone, whereby the vaporous fraction is treated to cracking conditions formative of high anti-knock gasoline in another separate zone;

and whereby the vapor cracked products While still at high cracking rate temperature, and the separated liquid fraction and/or heavy charge oil (preferably also at aacracking temperature) are commingled in still another-separate zone wherein the vapor phase cracking is decelerated, the liquid phase carckingrate accelerated, and the cracking continued to the desired degree.

In order that the invention may be better understood, reference is made to the accompanying diagrammatic drawings; Fig. 1 representing one form of apparatus suitable for carrying out the process, and Fig. 2 a simplified ow diagram Ahaving the same reference numbers as the corresponding instrumentalities of Fig. 1

Referring to the drawings: in the normal or preferred operation of the process the charging pump l delivers the raw stock to be treated (such as crude oil, reduced crude or heavy distillate) from any convenient source of supply (not shown) through the line 2, and heat exchanger 3, thence through lines 4 and 52 to contact hot cracked products issuing from coils 5 and/or 33'. However the charge oil may be heated to the desired temperature in any convenient manner, the place of introduction of the oil into the systembeing determined in accordance with its characteristics and the degree of refinement desired or required; i. e., oil to be distilled only may be introduced through line 4 and IB as controlled by valve 18', to contact hot fluid fiowing through line l. Oil to be treated to viscosity cracking, i. e., the preferred method of operation, is introduced through line 52, as controlled by valve 53 in the manner aforesaid.

When the recycle oil from the fractionating tower 20 is introduced by pump 22 to coil 5 alone, o1 in admixture with recycle oil withdrawn from separator 29, i. e., the preferred method; or optionally when the recycle oil separated in 29 is alone introduced into coil 5, the oil is heated therein to an active cracking temperature and discharging through line 34, as controlled by valve 34',-is directly admixed with the charge oil issuing from line 52 and in the normal operation further admixed with a portion of the cracked products eiiiuent of coil 33. This mixture is then treated in coil 5| to cracking conditions formative of desirable recycle oil, gasoline and low viscosity residual fractions.

Zone 5| is preferably a series of continuous connected pipes dimensioned and designed to assure an intimate physical contact of vaporous and liquid products during the treatment therein. Such coil arrangement may be also replaced by a chamber dimensioned and arranged to operate in the same manner.

' When the fresh charge oil introduced by pump l is of la composition liable to precipitate deleterious carbon upon cracking to the extent of substantial gasoline production but requires a decided viscosity reduction, it is preferably preheated to a degree that when admixed with the products eflluent of coils 5 and 33' the temperature in the coil 5I will be sufficient to effect the desired viscosity cracking under regulated conditions preventive of detrimental carbon formation therein.

In its passage through coil 5 the oil is heated to an extent that it will rapidly raise the charge oil to the desired cracking temperature when admixed therewith, or to an extent that when additional heat is supplied thereto by the cracked products efiluent of coil 33 a temperature will be immediately attained productive of further cracking thereof in coil 5l. The treatment in coil 5l is conducted without detrimental carbon formation and is of an order that upon releasing the thus treatedI mixed stock, as controlled by valve 5l, to the chamber 9 and. permitting partial vaporization to occur, the resultant residuum withdrawn through line I and cooler Il, as controlled by valve I0, is o f superior commercial characteristics, particularly as tovan improved cipie'nt cracking temperature with a predominantv portion of oil that is relatively refractory compared to said viscous oil (illustratively recycle gas oil), said refractory oil having been previously heated yto a'temperature (illustratively 800 to 900 F.) sufficient to substantially immediately raise the temperature of the viscous oil to an accelerated cracking temperature (illustratively 800 to 900 F.) when admixed therewith, but

without` material cracking of the refractory oil l occurring during heating; continuing the treatment of the mixture under sulcient pressure to prevent excessive vaporization of the refractory oil until the desired amount of viscosity cracking is attained, and then separating the mixture by vaporization. It will be noted that the above vrnethod of viscosity cracking is the previously mentioned preferred method of operation with emphasis directed to maintaining` a predominant mass of refractory solvent menstruum (recycle oil) in which the oil to be treated is cracked; the detailed operation when viscosityY cracking as above described being as follows: the oil to be treated to said cracking is delivered by pump Il through line 2, heat exchanger 3, line 52 and valve 53, where optionally admixed with a portion of oil from the bottom of separator 23 as delivered through line 30 and valve 30"', it is then commingled with one to twenty times its volume of recycle condensate issuing from coil through line 34, said condensate being withdrawn from the base of fractionator 2t and de livered by pump 22 through line 23 and valve 2t" to said coil, wherein it is heated in liquid or liquid-,vapor phase to an extent that without 'itself undergoing material cracking itwill heat the above oil or mixture sufficiently to effect the desired cracking, the thus heated recycle oil passing through pressure control valve dal' and is admixed as above stated. This mixture is then passed through valve 5l' into coil 5l wherein it is maintained for sufficient vduration to effect the desired further cracking but preventive of detrimentalcarbon formation, and under a pres-y sure as controlled by valve 5l inhibitive of excessive vaporization of asphaltene solvents. When viscosity cracking as above described, I prefer to admix the products effluent of coil 33 with the effluent of coil 5I by passing said products through line l as controlled by valves 8 thus departing from the normal method of precomminglement of `said products eiiluent with the` efliuent of coil 5 before passage through said coil 5|; and 8', although if the partial pressure effect of the light yproduct content of said eiiiuent does not cause excessive vaporization in coil 5|,

a portion of coil 33- effluent may be admixed (normal method) with the material entering coil 5l. I may also admix a portion of liquid delivered from separator 29 through line ,30 as controlled by valve 30" with the effluent of c ols 33 and 5l. In any case the thus treated products pass through line l into separator 3 where exists a pressure lower than previous and the residual products are separated as liquid from lighter products as vapor. It is to be understood that the treatment in coils 2l, 2l',' 33 and 33 is always substantially they same regardless of the operative conditions employed in coil 5l.

The vapor separating in the vaporizer 9 escapes through dome l2, to enter the partial'condenser I3, whence heavy reflux condensed therein is Withdrawn through line lli, as governed by valve l5, and charged through the agency of pump I6 discharging through line ll, via line t normally to heating coil 5 and/or optionally via lines t and 52 to coil 5l.

While the partial condensation of the vapors separated in 9 is not essential to the process, it is preferable to condense out the very heavy fractions of said vapor (accomplished in any wellknown manner) and treat such condensate to 'relatively mild cracking formative of fractions suitableto subsequent severer cracking conditions. This is accomplished in the present process by returning said condensate as above described and treating it to the crackingconditions estab lished in coils 5 and/or 5l. Further, I have found by the condensation and removal of such heavy fractions that the heavy condensate produced, separated and accumulated in the bottom of fractionator 20, is of more desirable'character for cracking under the herein prescribed treatment in coils 2l and 2l'.

The vapors separated in the partial condenser I3 and containing gasoline fractions produced under selective cracking treatments herein de-A scribed, escape through line i9 to enter the shell of exchanger 3, next discharging to bubble fractionating tower 20, whence condensed heavy recycle oil is withdrawn through line. 2l, as governed by valve 2 l The withdrawn oil is pumpedv Aby the high pressure pump 22 through line 23,

any desired portionA thereof not required for comminglement with the raw stock undergoing viscosity cracking being directed to coil 2l through heat exchanger 2t, or passed directly to vcoil 2l by proper manipulation of valves 23', 25 and 26', thence through line 26 to entersaid coil disposed in the left-hand convectional pass of furnace 6. The products from coil 2l enter the radiant coil 2li and flow therefrom via line 28 through the heat exchanger 2t, as controlled by valve. 20', to finally discharge into the high pressure vapor separator 29. It will also be noted that line 23, equipped with valve 2B, forms a connection with lines 23 and 30, through which the portion of heavy recycle oil employed as a cracking agent in the preferred method of operation is introduced into heating coil 5. It will also be noted that line 3l, equipped with valve 3l', forms a connection with line 32 through which a portion of the heavy recycle oil maybe passed through line 32 and coil 33. valve 3l is closed.

Vaporous fractions separating in the high Normally pressure vapor separator 29 pass oi through va- A vapor from 29 may'be condensed in a wellknown manner and the condensate delivered to coil 33 under the pressure of the separator 28 or by a pump.

Line 35 controlled by valve 35" extends to fractionator 20 for emergency use such as starting and stopping of operations; line 3| controlled by valve 3|' is used likewise, all of which valves being normally cloted; line 1 controlled by valves 8 and 8 is used as a by-pass for coil 5|. It is to be noted that the flow of gases through the zones containing the heating coils 5, 21 and 33 is controlled by regulation of dampers in the outlet of said zones and the waste gases are led to a stack (not shown).

The liquids separated in the high pressure vapor separator 29, may be released under its own y pressure through lines 36, 31 and 30, as controlled by valves 30', 30", 30"' and 38 and passed to the inlet of coil 5, or 5|, or to the outlet of coil 5|; or such liquid may flow to pump 4| and the pump pressure be imposed on line 3U during such distribution.

A portion of crude gasoline, naphtha or kerosene of relatively low octane rating, from any suitable source of supply 42, may be employed to supplement the fractions subjected to vapor phase treatment, and to such end may be conveniently introduced as trim stock to the high pressure vapor separator 29 through line 43, controlled by valve 43', to the suction of pump 44 and thence by lines 45 and 46, as controlled by valves 45 and 46', to the top of the separator; or such stock may be admitted via lines 45 and 41, as

controlled by valves 45', 46' and 41' to the uppery shell of heat exchangerp24, and thence via line 48, controlled by valve -48' to the mid-section of the separator 29', or such stock may be delivered as liquid to coil 33 by making suitable valve adjustments subsequently described.

A portion of the stock from tank 42 'may be admitted through lines 45 Aand 49, as controlled by valves 45', 45" and 49', to the coil of the partial condenser I3, thus serving to condense very heavy -fractions of the vapor leaving the chamber 9 while becoming itself preheated to a material degree.

It is preferable that the light stock to be subjected to vapor phase crackingy in coils 33 and 33' be substantially completely vaporized before entering said coils although it is within the scope of the invention to vaporize and crack such stock in the coils 33 and 33.

Further, a portion of the light stock supplied from extraneous source 42 or from accumulator 51, or mixtures thereof, may be passed in indirect heat exchange with the-products eiliuent of coil 5| in a well-known manner (not shown) to regulate the temperature thereof and to preheat the light stock.

The light stock discharged through the coil of the partial condenser I3 is forced under the obtaining pump pressure throughline 50 to the vapor phase cracking coil 33 and 33', disposed in the right-hand convectional pass of furnace 6. The cracked products from coils 33 and 33 pass through line '40, as controlled by valve 40' and enter the tube bank 5| while still undergoingv active cracking (normal method), or are passed through line 1 as controlled by valves 8 and 8' to be admixed with the effluent of coil 5| (practice employed in treating highly viscous oil) l It `will be observed that the products of coil 5 as controlled by valve 34' may be commingled with quantities of charge oil from line 52 as controlled by valve 53 (preferred operation), and/or with quantities of liquid from the bottom of separator 29 as controlled by valve 30"' (optional) and with quantities of the products eluent of coil 33' as controlled by valve 4U' and the mixture passed through coil 5I as controlled by valves 5| and 5|" (preferred operation); or the products of coil 5 may be admixed with charge oil only and this mixture passed through coil 5|, while the products eiiluent of coil 33' and the liquid from the bottom of separator 29 are admixed with the effluent of coil 5| (practice employed in treating highly viscous oil) these various operations being accomvplished by proper setting of valves provided for the purpose, and commonly understood by those Skilled in the art to which the invention relates. Heavy condensate from the partial condenser I3, as delivered by pump |6 may likewise be delivered in selective quantities through lines 4 and/or 52 as controlled by valves 4', 4" and 53 to be admixed with the products entering coil 5 or 5|.

Light recycle oil may be selectively withdrawn from the bubble tower 20 by lines 54, 55 and 56, asvrespectively controlled by valves 54', 55' and 56 and accumulated in tank 51, whence portions thereof may be pumped by pump 58 via lines 45, 46, 41, 48 and 49 to the coil of the partial condenser I3. or to separator 29 by a proper setting of valves 45', 45", 45"', 46', 41', 48', 49', 23 and 25', and thereafter to the vapor phase cracking coil 33 and 33 for recracking treatment therein. Light vapors separating in the accumulator 51 are returned to the bubble tower 20 by line 59 as controlled by valve 59'.

It is a feature of the process to so regulate the flow through the various cracking zones that the selective fractions concurrently subjected to their respective heat treatments will be cracked to the desired degree without formation of detrimental carbon, not only during the active cracking periods, but in any subsequent treatment of the cracked products. To this latter end it is essential to entirely stop or decelerate the cracking rate of the complex fractions contained in the eiiluent of the zone 5|, this being aecomplished in any one of the following ways, or combinations thereof; such as normally cooling the products efliuent of the nal reaction zone before or after pressure release by direct admixture with a cooling medium, preferably cooler oil; or by indirect heat exchange with a cooler fluid substance; or by regulation of duration of separated residual oil in separator 9 by withdrawing the separated residual products therefrom substantially immediately on separation,

Gasoline vapors fractionated in the bubble tower 20 pass off through vapor line 60 to condenser 6I. The condensate therefrom flows through line 62 to accumulate in receiver 63 from whence liquid gasoline is withdrawn from the system through line 64, as controlled by valve Fixed gas escapes through line 65, as controlled by valve 65', which is preferably of automatic operation. Any gasoline necessary for trim control may be withdrawn from receiver 63 by line y|36, and pumped by pump 61 through line 58 to trim spray coil 69.

It is to be further understood that the appal ratus is equipped with suitable indicating and recording devices for observation and registration of pressures, temperatures, flow, etc., and that the apparatus is insulated where it is desirable to maintain or regulate heat. Furth-er, the invention is not limited to the particular form of apparatus herein described, nor to the specific aosaseo temperatures and pressures mentioned, which are given by way of example only.

What I claim as new and desire to protect by' Letters Patent is:

1. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling heavy hydrocarbon such as crude petroleum or reduced crude with hotter, fluid hydrocarbon, imposing through such comminglementl cracking conditions of heat and pressure on said heavy hydrocarbon, reducing the viscosity thereof by continuing said cracking conditions, separating generated vapors from residuum and withgling products of such cracking treatments as said hotter, fluid hydrocarbon with said heavy hydrocarbon and continuing the process in the manner aforesaid. l

2. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with hotter, fluid hydrocarbon and accelerating thereby the cracking rate, of said heavy hydrocarbon, reducing the viscosity of said heavy hydrocarbon by continuing such` accelerated cracking rate, separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the va.- pors tocondense and separate reflux bondensate from gasoline vapors and separately condensing the latter as anti-knock gasoline, subjecting the reflux condensate` to cracking conditions of heat and pressure, separating generated vaporous fractions from residual fractions and separately subjecting such fractions to liquid and vapor phase cracking respectively, commingling products of such cracking treatments as said hotter, fluid hydrocarbon with said heavy hydrocarbon and continuing the process in the manner aforesaid.

3. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises comrningling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a stream of hotter, fluid hydrocarbon, accelerating thereby the cracking rate of said heavy hydrocarbon and reducing the viscosity thereof by continuing such accelerated cracking rate for an interval short of detrimental carbon separation, generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to condense and separate reflux condensate from gasoline vapors and separately condensingI the latter as anti-knock gasoline, subjecting the reflux condensate to liquid .phase cracking conditions of heat and pressure for an interval short of substantial asphaltic degradation, separating generated vaporous fractions from residual fractions before detrimental asphaltenes obtain, subjecting the vaporous fractions to vapor phase cracking for an interval short of detrimental carbon formation, uniting 'the products of such vapor phase cracking at their cracking temperature with residual fractions as said hotter, fluid hydrocarbon, comseparating bon such as crude petroleum o'r reduced crude mingling the latter with said heavy hydrocarbon ailingl continuing the process in the manner aforesa 4. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to 'X75-900 F. with a stream of hotter, fluid hydrocarbon, accelerating thereby the cracking rate of said heavy hydrocarbon, reducing the vis-Y cosity and increasing the light fraction content thereof by prolonging such accelerated cracking rate under a pressure preventive of complete vaporization and for an interval short of detrimental carbon formation,.separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to" condense and separate reux condensate from gasoline vapors and separately condensing the latter as anti-knock gasoline, subjecting the reflux condensate to S-925 F. under 10G-1000 lbs. pressure for an interval'short of detrimental carbon formation, separating generated vaporous fractions from residual fractions as products boiling under and above' approximately 625 F. respectively, subjecting the vaporous fractions to vapor phase cracking at 925-1125 F. for an interval short of detrimental carbon formation, uniting the products of such vapor phase treatment with the residual fractions substantially at their respective cracking temperatures as said hotter, fluid hydrocarbon, commingling the latter with said heavy hydrocarbon and continuing the process in the m manner aforesaid.

5. Process for producing anti-knock gasoline and low viscosity fuel oil lwhich comprises commingling a stream of heavy-hydrocarbon such as crude petroleum or reduced crude heated to vF75-900 F. with a stream of hotter, iiuid hydrocarbon, accelerating thereby the cracking rate of said heavy hydrocarbon, reducing the viscosity and increasing the light fraction content thereof by prolonging such accelerated cracking rate under a pressure preventive of complete Vaporization and for an interval short of detrimental carbon formation, separating generated vapors from residuum andA withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to `condense and separate reflux condensate from phase treatment with the residual fractions substantially at their respective cracking temperatures as said hotter, fluid hydrocarbon, commingling the latter with said heavy hydrocarbon and continuing the process in the manner aforesaid. y

6. Process for producing anti-knock gasoline which `comprises ,commingling heavy hydrocarheated to 'a cracking temperature with hotter,

fluid hydrocarbon', respectively accelerating and w decelerating thereby the cracking rate of said heavy and said iiuid hydrocarbons, continuing ed to liquid and vapor phase cracking, separating the residual fractions from the vaporous fractions and subjecting the latter to vapor phase cracking, commingling the products of such vapor phase treatment while still at a high cracking rate, as said hotter, fluid hydrocarbon, with a. mixture of said residual fractions and said heavy hydrocarbon, and continuing the process in the manner aforesaid.

7. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a stream of hotter,

fluid hydrocarbon, respectively accelerating and decelerating thereby the cracking rate of said heavy and said fluid hydrocarbons, reducing the viscosity and increasing the light fraction content of said heavy hydrocarbon by continuing sch resultant cracking rate for an interval short of detrimental carbon formation, separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to condense and separate recycle oil from gasoline vapors and separately condensing the latter as anti-knock gasoline, subjecting the recycle oil in two portions to separate liquid phase cracking conditions of heat and pressure best suited to produce residual and vaporous fractions adapted to liquid and vapor phase cracking, separating the residual from the vaporous fractions and subjecting the latter to vapor phase cracking, admixing the unseparated products of liquid phase cracking of the other portion of the recycle oil with said residual fractions and uniting such admixture with the products of said vapor phase cracking as said hotter, fluid hydrocarbon, commingling the latter with said heavy hydrocarbon and continuing the process in the manner aforesaid.

8. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a stream of hotter, fluid hydrocarbon, respectively accelerating and decelerating thereby the cracking rate of said heavy and said fluid hydrocarbons, reducing the viscosity and increasing the light fraction content of said heavy hydrocarbon vby continuing such resultant cracking rate short of detrimental carbon formation, separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to 'condense and separate recycle oil from gasoline vaporsand separately condensing the latter as anti-knock gasoline, subjecting a portion of the recycle oil to liquid phase cracking conditions of heat and pressure best suited to produce residual and vaporous fractions respectively adapted to liquid and vapor phase cracking, separating the residual fractions from the vaporous fractions and subjecting the latter to vapor phase cracking, admixing the residual fractions with another portion of the recycle oil `and subjecting such mixture to liquid phase cracking conditions, uniting the products of such treatment with the products of said vapor phase cracking while still at a high cracking rate, as said hotter, fluid hydrocarbon, commingling the latter with said heavy hydrocarbon and continuing the process in the manner aforesaid.

9. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a stream of hotter. fluid hydrocarbon, respectively accelerating and decelerating thereby the cracking rate of said heavy and said fluid hydrocarbons, reducing the viscosity and increasing the light fraction content of said heavy hydrocarbon by continuing such resultant cracking rate short of detrimental carbon formation, separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to condense and separate recycle oil from gasoline vapors and separately condensing the latter as anti-knock gasoline, subjecting a portion of' the recycle oil to liquid phase cracking conditions of heat and pressure best suited to produce residual and vaporous fractions respectively adapted to liquid and vapor phase cracking, separating the residual fractions from the vaporous fractions and subjecting the latter to vapor phase cracking, subjecting the residual fractions to liquid phase cracking conditions, uniting the products of such treatment with the products of said vapor phase cracking while still at a high cracking yrate, as said hotter, fluid hydrocarbon, commingling the latterwith said heavy hydrocarbon and continuing the process in the manner aforesaid.

10. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a stream of hotter, fluid hydrocarbon, respectively accelerating and decelerating thereby the cracking rate of said heavy and said fluid hydrocarbons, reducing the viscosity and increasing the light fraction content of said heavy hydrocarbon by continuing such resultant cracking rate for an interval short of' carbon formation, admixing the products of such treatment with products of vapor phase cracking at their respective cracking temperatures, seperating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil. dephlegmating the vapors to condense and separate recycle oil from gasoline vapors and separately condensing the latter as anti-knock gasoline, subjecting the recycle oil inv two portions to separate liquid phase cracking conditions of heat and pressure, separating one portion so treated into residual fractions and vaporous fractions and subjecting the latter to vapor phase cracking, commingling the unseparated products of liquid phase cracking of the other portion of the recycle oil, as said hotter, fluid hydrocarbon.

`decelerating therebythe cracking rate of said -heavy and said fluid hydrocarbons, reducing the ,treatment with products of vapor phase cracking at their respective cracking temperatures, separating generated vapors from residuum and withdrawing the latter as low viscosityfuel oil, dephlegmating the vapors to condense and separate recycle oil from gasoline vapors and separately condensing the latter as anti-knock gasoline, subjecting the recycle oil in two portions to separate liquid phase cracking conditions of heat and pressure, separating one portion so treated into residual fractions and vaporous fractions and subjecting the latter to vapor phase cracking, clommingling the unseparated products of liquid phase cracking of the other portion of the recycle oil, as said hotter, uid hydrocarbon, in a relatively large ratio with said heavy hydrocarbon, and continuing the process in the manner aforesaid.

12. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a streani of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a, stream of hotter, fluid hydrocarbon, respectively accelerating and decelerating thereby the cracking rate of said heavy and said fluid hydrocarbons, reducing the viscosity and increasing the light fraction content of said heavy hydrocarbon by continuing such resultant cracking rate for an interval short of carbon formation, admixing the products of such treatment with products of vapor phase cracking at their respective cracking temperatures, separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmatng the vapors to condense and separate recycle oil from gasoline vapors and sep-v arately condensing the latter as anti-knock gasoline, subjecting the recycle oil in two portions to separate liquid phase vcracking conditions of heat and pressure, separating one portion so treated into residual fractions and vaporous fractions and subjecting the latter to vapor phase cracking, admixing the unseparated products of liquid phase cracking of the other portion of the recycle oil with the residual fractions, as said hotter, fluid hydrocarbon, commingling the latter with said heavyhydrocarbon and continuing the process in the manner aforesaid.

13. Process for producing anti-knock gasoline and low viscosity fuel oil which comprises commingling a stream of heavy hydrocarbon such as crude petroleum or reduced crude heated to a cracking temperature with a. stream of hotter, fluid hydrocarbon, respectively accelerating and decelerating thereby the cracking rate of said vheavy and said fluid hydrocarbons', reducing the viscosity and increasing the light fraction content of said heavy hydrocarbon by continuing such resultant cracking rate for an interval short of carbon formation,l admixing the products of such treatment with products of vapor phase cracking at their respective cracking' temperatures, separating generated vapors from residuum and withdrawing the latter as low viscosity fuel oil, dephlegmating the vapors to condense and separate recycle oil from gasoline vaporsy and separately condensing the latter as anti-knock gasoline,` subjecting the recycle oil in two portions to separate liquid phase cracking conditions of heat and pressure, separating one portion so treated into residual fractions and vaporous fractions and subjecting the latter to va'por phase cracking, admixing the vunseparated products of liquid phase cracking of the other portion of the recycle oil with the residual fractions, and theremaining portions of the products of vapor phase cracking, as said hotter, fluid hydrocarbon, commingling the latter with said heavy hydrocarbon and `continuing the process in the manner aforesaid.

A JOSEPH F. DONNELLY. 

